The present invention relates to a semiconductor pressure sensor to be assembled on a printed circuit board, and more particularly to a semiconductor pressure sensor suitable for measuring the pressure of the intake air of the engine of an automobile.
A semiconductor pressure sensor of this type is disclosed in U.S. Pat. No. 4,413,527, for example. The conventional sensor disclosed in this U.S. Patent comprises: a housing; a sensor board located in the housing; a sensor chip assembled on the sensor board; and a circuit unit assembled on the sensor board and used for processing electric signals supplied from the sensor chip. The interior of the housing is filled with synthetic resin, so as to protect the circuit unit from water and oil. In other words, the circuit unit is embedded in a filler formed of the synthetic resin.
Since the interior of the housing is filled with the filler, the sensor chip is enclosed in a metal package, thereby protecting the sensor chip from the filler. With this construction, however, a sensor unit, which is constituted by the sensor chip and the metal packaging, is inevitably large, due to the restrictions in the manufacturing of the package. Accordingly, the semiconductor pressure sensor itself is inevitably large. Furthermore, the sensor of the U.S. Patent must use a pressure-introducing pipe which extends through the package in an airtight manner, so as to guide the pressure medium to be measured to the sensor chip. The sensor disclosed in U.S. Pat. No. 4,413,527 must also use a plurality of connecting pins which extend through the package in an airtight manner and electrically connect the sensor chip and the sensor board to each other to supply electric signals from the sensor chip to the outside of the package.
Accordingly, as long as a sensor unit is formed by enclosing a sensor chip with a metal package, the semiconductor pressure sensor has the following problems: the sensor unit itself is large and a large number of parts are required, thereby complicating the construction of the sensor due to the necessity of using the pressure-introducing pipe and connecting pins.